Airport boundary light



Nov. 19, 1935. 1'. w. ROLPH "AIRPORT BOUNDARY LIGHT Filed Aug. 1. 1931 INVENTOR TTORNEY Patented Nov. 19 1935 UNITED STATES PATENT- OFFICE 2,0,811. AIRPORT BOUNDARY LIGHT Thomas W. Bolph, Newark, Ohio, asslgnor to Holophane Company, Inc., New York, N. Y a j corporation of Delaware 1 Application August 1.- 19:1, sci-m No. 554,486 Claims. (ciao-1.2)

The present invention relates to airport boundary lights and is more particularly directed toward such lights designed to give a signal to the aviator distant from the landing fleld and at an elevation suitable for gliding to a landing.

' The present invention contemplates a boundary obtains the primary beam by means of a prismatic refractor preferably with a wide vertical angle of acceptance and arranged to send out the light in an upwardly inclined beam at an angle to the horizontal substantially that of the gliding angle of an airplane, or at an angle of from 4 to 12 above the horizontal. I

A further object of the invention is to provide an outdoor lighting luminair with a refractor designed to give the desired signal and having a smooth outer surface, preferably provided by a totally enclosing envelope of pressed or blown glass which protects the reiractor. This envelope may be of clear or colored glass, depending upon the color of light desired, and when the colored glass is employed in the envelope instead of in the reiractor, it is possible to obtain more uniform color value and hue in the emitted beam. A fur- 1 ther object of the invention is to design the luminair so that the glass parts may be preassembled as a unit which may be placed on the support or removed from it without disassembling the glass.

The accompanying drawing. shows, for purposes of illustrating the present invention, several embodiments in which the invention may take form, it being understood that the drawing is illustrative of theinvention rather than limiting the same. e I

In this drawing: 1

Fig. 1 is a side elevational view of a complete boundary lighting unit illustrating a luminair and boundary cone; g

2 is a vertical sectional view through ans form of boundary light; J

Fig. 3-is a fragmentary sectional view through the lower portion of a modified form of boundary light of the type shown in Fig. 2; and

glass member.

Figs. 4 and 5 are vertical sectional viewsv illustrating other modified forms of construction.

In the drawing the support for the boundary light is indicated in a form of metal fltter l hav-, ing an internally threaded hole I I by which it may be mounted on an upright support. The iltter II has an internal lflange l2 located below internal threads I! adapted to receive the glass part. A lamp socket It is secured'to the flange l2 either directly as shown in Fig. 5 or by means of a m bridging member is as indicated in Figs. 2 and 3. The lamp socket It supports a lamp bulb i having a concentrated light source L. Where the unit is for use with boundary cones it is mounted above boundary cone C as indicated in Fig. 1, i

In the form shown in Fig. 2, the unit has three glass parts 20, 2|, and 22, all of which may be symmetrical about a vertical axis. The lower glass part has a threaded neck 23 to be received within the ,fltter Ill and adapted tobe threaded 20 down against a gasket 24. This glass part extends upwardly .and outwardly as indicated in the drawing and is provided with internal ribbings 25 adapted to diffuse the light, as indicated at A,.A'. The upper'portion of the glass member 20 is provided with a flange 20 having anannular rib 21 in its upper face.

Glass member 2| is a refractor and is provided with a suitable prismatic formation to redirect the light somewhat as indicated by the light rays B, B. It will be noted that refractor 2! is of generally conical shape, that its lower edge rests on the upper face of'the lower member 20, and that it is closed at the top 29. v

The outer envelope 22 of pressed or blown glass, clear or colored, has its lower edge 30 resting on the periphery of the flange 26 of the lower The parts 22 and 20 are clamped together by c-shaped clamps 3|. A spring 32 interposed between the cover g'lass'22 and the re- 40 'fractor 2| acts to hold the refr'actor in position so that the glass parts 20, 2|, and 22 may form a preassembled unit. The opening in the threaded neck of the lower glass part'is somewhat larger than the lamp bulb 16 so that one can remove the glass parts past the lamp bulb.

"The light distribution of the boundary light shown in Fig. 2 is illustrated by the photometric curve B of Fig. 1 It will be seen that this curve shows .a primary beam pprojected upwardly at 5 angle of about which is approximately the average gliding angle of airplanes, and that I .the lower secondary beam S is. projected downwardly and outwardly diverging at an angle of about 15 from man. This beam of light is in- 5 wardly to be redirected by the upper glass mem-' ber 2| thereby reinforcing the primary beam.

In the construction shown in Fig. 4, the outer envelope 22' is provded with internal prisms 33 designed to further concentrate the light and with shallow vertical flutes 34 to give some lateral diffusion and better appearance to the globe without .materially affecting the vertical distribution.

The unit of the type shown in Figs. 2 and 4 has a very .wide vertical angle of acceptance. All the light emitted by the lamp is eflectively utilized and inasmuch as the refractor 2| extends a very substantial distance below the light source L, the largest proportion of the emitted light on the lamp is handled by this refractor and redirected into the desired direction.

In the form of unit shown in Fig. 5 the outer protective envelope is dispensed with. The outer surface of the refractor 40 is smooth and the inner prisms II are designed to direct the light outwardly and upwardly at an angle of approximately 7.5". The lower glass member 42 is provided with external reflecting prisms 43 adapted to return most of the light upwardly as indicated by the arrows D, D.

What is claimed is:

. 1. An airport boundary light adapted to function as a signal to an aviator and comprising a support carrying an upwardly extending light source and an upwardly and outwardly flaring light transmitting member for transmitting .the lower portion of the downwardly emitted light into a secondary diverging beam, and a refractor whose lower edge rests on the lower transmitting mem- 5 her adjacent the periphery thereof, the refractor having annular prisms extending from below the horizontal plane of the light source substantially to zenith, the prisms accepting all the light emitted above the transmitting member and being 10 adapted to concentrate the light into an intensive primary beam with its angle of maximum intensity inclined slightly upwardly above the horizontal for signalling purposes to the aviator.

2. An airport boundary light as claimed in claim 1, wherein a protective envelope rests on the periphery of the lower light transmitting member and covers the entire refractor.

3. An airport boundary light adapted to function as a signal to an aviator and comprising a support carrying an upwardly extending light source and an upwardly and outwardly flaring light transmitting member for transmitting a portion of the downwardly emitted light into a secondary diverging beam for illuminating a boundary cone below the support, and a refractor of generally conical shape closed at the top and having its lower edge resting on the lower transmitting member adjacent the periphery thereof, the refractor having annular prisms accepting light through an angle substantially greater than 90 measured from zenith to concentrate the light into an intensive primary beam with its angle of maximum intensity inclined slightly upwardly above the horizontal to provide a continuous bright signal while gliding to a landing in the I field of the airport. 

